1985258129 has 4 divisors (see below), whose sum is σ = 1985406900. Its totient is φ = 1985109360.

The previous prime is 1985258123. The next prime is 1985258161. The reversal of 1985258129 is 9218525891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9218525891 = 83 ⋅111066577.

It can be written as a sum of positive squares in 2 ways, for example, as 1122250000 + 863008129 = 33500^2 + 29377^2 .

It is a cyclic number.

It is not a de Polignac number, because 1985258129 - 2⁸ = 1985257873 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1985258123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52154 + ... + 81795.

It is an arithmetic number, because the mean of its divisors is an integer number (496351725).

Almost surely, 2^1985258129 is an apocalyptic number.

It is an amenable number.

1985258129 is a deficient number, since it is larger than the sum of its proper divisors (148771).

1985258129 is a wasteful number, since it uses less digits than its factorization.

1985258129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148770.

The product of its digits is 518400, while the sum is 50.

The square root of 1985258129 is about 44556.2355793216. The cubic root of 1985258129 is about 1256.8178138441.

The spelling of 1985258129 in words is "one billion, nine hundred eighty-five million, two hundred fifty-eight thousand, one hundred twenty-nine".